Novel antitumour indole alkaloid, Jerantinine A, evokes potent G2/M cell cycle arrest targeting microtubules

Summary Natural products play a pivotal role in the treatment of cancer; identification of compounds such as taxanes and the vinca alkaloids were seminal landmarks in natural product drug discovery. Jerantinine A, a novel Aspidosperma alkaloid isolated from plant species Tabernaemontana corymbosa , was previously reported to possess cytotoxic activity against vincristine-resistant nasopharyngeal carcinoma cells and is therefore an ideal candidate for biological investigation. Furthermore, Tabernaemontana corymbosa , has been placed in the endangered list of threatened species by the International Union for Conservation of Nature thus making it a priority to elucidate the biological activity of this alkaloid. Herein, we report detailed biological evaluation of jerantinine A on various human-derived carcinoma cell lines. Our preliminary screens showed that significant inhibition of cell growth and colony formation accompanied time- and dose-dependent induction of apoptosis in human cancer cell lines after treatment with jerantinine A. Dose-dependent accumulations of cleaved PARP and caspase 3 further confirmed apoptosis. Profound G2/M cell cycle arrest was observed 24 h after treatment in all cell lines. Characteristics of mitotic arrest including inhibition of tubulin polymerisation, microtubule disruption, aneuploidy, and cyclin B1 down-regulation were clearly observed. The potent anti-proliferative, pro-apoptotic, and tubulin-destabilising activities of jerantinine A warrant further development of this molecule as a potential chemotherapeutic agent.